New research reveals longevity gains slowing, life expectancy of 100 unlikely

This is not true and easily countered by any sort of investigation. Lobsters, flatworms, immortal jellyfish and hydras are all believed to be immortal.

In fact we know how to live forever, control our telomeres. We know it works because cancer exists. We just can’t control it but controlled cancer is effectively immortality.

Is it true that those creatures are believed to be immortal or we’ve just never seen one die of natural causes?

Cancer is a parasitism that kills the host (or the host dies from other causes and it is not self-sufficient). Just because something is defined by uncontrolled self-replication doesn’t mean it is stable to live forever (Which is as much a comment on homeostasis as self-renewal)

I believe one listed converts back to a polyp form under bad conditions and just has another go.

[EDIT: Biologically] immortal doesn’t mean indestructible. It just means they don’t age.

Lobsters aren’t truly biologically immortal. They “continue to grow throughout their lives,” with “increasing amounts of energy” being needed to mount ans they grow larger [1]. “Eventually the cost is too high and lobsters can die from exhaustion.” (That said, if our cells aged like lobsters we’d live something like thousands of healthy years.)

For true biological immortality, look to some jellyfish [2]. You literally can’t tell if a cell is taken from an old or juvenile.

[1] https://www.nhm.ac.uk/discover/are-lobsters-immortal.html

[2] https://www.nhm.ac.uk/discover/immortal-jellyfish-secret-to-...

> Immortal doesn’t mean indestructible. It just means they don’t age.

Technically “immortal” means “never dying”, it has nothing to do with age. You could be unable to die but continue to age and become ever more decrepit (although the Oxford dictionary does list “never decaying” in its definition), for sure there’s a sci-fi short story about that out there.

The mentioned creatures all age, they do get older, it just so happens their bodies don’t deteriorate, or they do but regenerate.

> Technically “immortal” means “never dying”, it has nothing to do with age

Hence my use of the term biologically immortal.

> mentioned creatures all age, they do get older, it just so happens their bodies don’t deteriorate

Were you really confused that OP was talking about stopping physical time?

> Hence my use of the term biologically immortal.

That’s the second paragraph. I was specifically addressing only the first (the one I quoted). In that one you seem to be saying that “immortal means not aging”. That’s the only part of your post I wanted to address, the rest was very clear.

> Lobsters, flatworms, immortal jellyfish and hydras are all believed to be immortal.

What is the oldest known living individual for each of these species, and for how long are they alive?

> What is the oldest known living individual for each of these species, and for how long are they alive?

For the jellyfish, we don’t know. Their cells are indifferentiable by age and they’re bastards to study, with only one scientist in Kyoto having managed to culture them [1].

[1] https://en.m.wikipedia.org/wiki/Turritopsis_dohrnii

Got it, thank you. Edited for clarity.

Lobsters die of old age when they fail to molt, become trapped in their shells, and starve. The lobster body plan does not scale indefinitely. Presumably at a certain point they'd boil in their own metabolic heat.